A reconstruction system of the aforementioned type is known from document EP 2 302 362 A1. It comprises a plurality of pulsed radiation sources to illuminate the medium of which one wishes to acquire an image, then process it, and a plurality of detectors receiving the signals emitted by the illuminated medium. Each pulsed source is a pulsed laser source or an optical fiber connected to an offboard pulsed laser.
Each detector is a time-resolved detector, i.e. a detector making it possible to measure the time distribution of the arrival time of the photons, also called TCPSC (Time-Correlated Single Photon Counting). According to a first embodiment, each detector includes a photomultiplier tube connected to an optical fiber transmitting the signal from the studied medium to the detector. According to a second embodiment, each detector includes a set of pixels of an intensified camera with a time gate, also called ultra-fast intensified gated camera.
The reconstruction system comprises means for producing, for each source-detector pair, a time distribution of the signal received by the detector, and a device for determining, as a function of the moments of order 0 and order 1 of the time distribution for each source-detector pair, the localization of the fluorophores(s) arranged in the medium.
However, the detectors of such a reconstruction system have a time and/or amplitude instability, which creates uncertainties affecting the time distribution. The determination of the optical properties of a diffusing medium require considering transforms of such distributions, in particular Mellin transforms, these transforms making it possible for example to establish moments of order 0 or order 1 used during the reconstruction process. It is then understood that these instabilities can affect the precision of the reconstruction.
The aim of the invention is therefore to propose a reconstruction system for the optical properties of a diffusing medium, making it possible to reduce the influence of parasitic fluctuations of the time distributions obtained by the time-resolved optical detectors, so as to improve the reconstruction of the optical properties.